Just curious to what types of traps people set, or even general strategy.

One trap i like is using the outside wall. i start a bit a way from the wall leaving a tunnel behind me, then go for a second or two and then move right next to the wall creating a place if you go you crash into the wall. It's a great way to trap the outside wall hugger.

Actually, there are a lot of people in Nexus9 that go immediately for the rim at start. Some do it just to avoid the chaos at the beginning when there are 12+ cycles trying to gain position, but some people go for the wall and just stay there.

My strategy doesn't involve a trap necessarily, but trying to carve out as big a section of the center as possible, since often you will be forced to go back through there later in the round. The other thing I do is attempt to bisect the grid at start. Of course, these are pretty weak strategies for the amount of effort it takes to set them up.

I leave ropes laying around with little circles tied in them. Once a person steps in, the rope gets pulled up by a big wooden spring sometimes called a tree branch and the person hangs from their feet.

An extra rope pulling the branch down, released by a trigger. I do think those things only work on humans in the movies, the volume the trap uses (Tree bent down) is too large compared to the area you have to step in. Using heavy stones as a counterweight sounds like a better idea to me, it's less cruel to the poor tree. Or go with spiked pits.